Dorman M39580 Brake Master Cylinder

Reliable Brake Master Cylinder for Buick, Cadillac, Oldsmobile, and Pontiac

The Dorman M39580 brake master cylinder is engineered to restore proper brake hydraulics in select Buick, Cadillac, Oldsmobile, and Pontiac models. Designed with precision, this aluminum master cylinder includes a reservoir and features dual bore diameters to meet specific braking system requirements.

• Compatible with Buick 98, Bonneville, Custom Cruiser, Delta 88, LeSabre
• Fits Cadillac DeVille and Fleetwood models
• Aluminum construction for durability and corrosion resistance
• Includes reservoir for fluid storage
• Dual master cylinder bore diameters: 24mm and 36mm
• Four outlet ports with rearward outlet sizes M11 x 1.5 and M16 x 1.5
• Part number M39580 for accurate identification

Technical Details and Specifications

The Dorman M39580 brake master cylinder is crafted from aluminum, providing a lightweight yet durable component essential for brake hydraulics. It features two bore diameters, 24mm and 36mm, to accommodate the specific brake system design of various GM vehicles. The included reservoir ensures proper brake fluid containment, while the four outlet ports with rearward outlet thread diameters of M11 x 1.5 and M16 x 1.5 allow for secure brake line connections. This master cylinder does not include mounting hardware or sensors, focusing on core hydraulic functionality.

Common Applications and Problem Resolution

• Restores brake pressure in Buick 98 and Pontiac Bonneville models
• Replaces worn or leaking master cylinders in Cadillac DeVille and Fleetwood
• Addresses brake fluid leaks and loss of hydraulic pressure
• Solves spongy or unresponsive brake pedal issues
• Prevents brake system failure due to master cylinder wear

Installation Notes and Tips

Installation of the Dorman M39580 brake master cylinder requires proper brake system bleeding to remove air and ensure optimal performance. Since mounting hardware is not included, retain original fasteners or source compatible replacements. Verify outlet thread sizes (M11 x 1.5 and M16 x 1.5) to match brake lines. This part is designed for direct replacement on compatible Buick, Cadillac, Oldsmobile, and Pontiac models listed.

Quality Assurance and Warranty Information

Dorman brake master cylinders undergo rigorous testing to meet OEM standards for fit, form, and function. The M39580 part is backed by Dorman's limited warranty, covering defects in material and workmanship to provide confidence in long-term reliability.